In May 2026, Acta Physico-Chimica Sinica published the latest photocatalysis research from the teams of Associate Professor Qing Li at Hubei University and Professor Guangfu Liao at Fujian Agriculture and Forestry University.
The study reports a carbon nitride system in which pyridine rings serve as electron traps. Specific adsorption sites, including –C=O, –OH, and –NH₂ groups, were successfully introduced, while a rapid electron-delocalization pathway dependent on the pyridine-ring structure was constructed. This design effectively promoted O₂ activation and provides a new example of targeted molecular engineering for carbon nitride photocatalysts.
The first author of the paper is Yuan Xue. Associate Professor Qing Li and Professor Guangfu Liao are the corresponding authors.
Hydrogen peroxide (H₂O₂) is a high-value green energy carrier with broad applications in chemical synthesis, medical disinfection, wastewater treatment, and other fields. As market demand continues to increase, the development of efficient and sustainable H₂O₂ production technologies has become increasingly important.
Compared with the conventional industrial anthraquinone process, photocatalytic H₂O₂ synthesis offers a more sustainable route by using abundant solar energy. It can operate under milder reaction conditions and with lower energy consumption. However, its efficiency is highly dependent on the intrinsic characteristics of the catalyst, including its band structure, active sites, and interfacial charge-carrier dynamics. Developing high-performance photocatalysts is therefore essential for advancing photocatalytic H₂O₂ production.
A wide range of photocatalysts has been investigated, including metal-organic frameworks, covalent organic frameworks, graphitic carbon nitride (g-C₃N₄), polymer resins, metal oxides, and metal sulfides. Among these materials, g-C₃N₄ has attracted considerable attention because of its straightforward synthesis, excellent chemical stability, and favorable light-response properties.
Nevertheless, the limited number of active sites in g-C₃N₄ restricts O₂ adsorption, while rapid recombination of photogenerated charge carriers limits H₂O₂ generation. Because the molecular structure of g-C₃N₄ is highly tunable, introducing organic functional groups at the framework edges can regulate the band structure, charge-separation and transfer behavior, and O₂ activation capability. The targeted incorporation of electron-trapping groups is therefore one of the most direct and effective strategies for controlling charge separation.
The study used the Perfectlight PLS-CS300 Xenon Lamp Light Source.
Through structural optimization of the lamp housing and improvements to the light-guiding system, the PLS-CS300 delivers substantially higher optical output power. Test results show that, under different current conditions and with other parameters such as irradiation distance kept unchanged, the optical power increased by more than 30%. This level of improvement can support faster, broader, and more efficient photocatalytic applications.
The samples were prepared through thermal polymerization followed by amidation. Scanning and transmission electron microscopy showed that pristine carbon nitride (PCN) formed aggregated block-like stacks, whereas the functionalized N-CN, HN-CN, and AN-CN samples exhibited hollow, fluffy, hexagonal-prismatic tubular structures with diameters of approximately 5 μm.
X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and solid-state 13C nuclear magnetic resonance measurements indicated that the functional groups in the three modified materials were grafted only onto the PCN surface and were introduced in very small amounts.
Figure 1. Schematic illustration of sample synthesis, morphology, and basic structural characterization.
Under visible-light irradiation, N-CN, HN-CN, and AN-CN all exhibited substantially higher photocatalytic H₂O₂ production rates than PCN. The activities of N-CN and HN-CN were 3.6 and 5.8 times that of PCN, respectively. AN-CN achieved an outstanding H₂O₂ production rate of 2798 μmol g−1 h−1, representing an 8.7-fold improvement over PCN. The catalyst concentration was maintained at 1 mg mL−1 throughout the reaction.
Figure 2. Photocatalytic H₂O₂ production performance of the samples.
The exciton lifetimes of N-CN, HN-CN, and AN-CN were significantly shortened, indicating that the pyridine-ring structure and the –OH/–NH₂ functional groups synergistically promoted exciton dissociation. The suitable band positions of the catalysts also ensured the thermodynamic feasibility of the two-electron oxygen-reduction reaction.
Figure 3. Optical and photoelectrochemical properties of the samples.
Analysis of the time constants τ1 and τ2 showed that AN-CN possessed a longer carrier lifetime and average lifetime than N-CN and HN-CN. This behavior induced long-lived shallow charge trapping, improved the utilization of photogenerated electrons, increased photoelectron density, and enhanced photocatalytic performance.
Figure 4. Transient absorption spectra of the samples from femtosecond to nanosecond timescales.
The pyridine ring/–C=O structure induced electron migration from the tri-s-triazine units toward the pyridine rings, thereby improving electron-hole separation. The additional –OH and –NH₂ groups acted synergistically with the pyridine rings to provide a stronger driving force for carrier migration than that of the pyridine-only system, further promoting photocatalytic H₂O₂ production.
In addition, the lone-pair electrons of –NH₂ acted as electron donors and injected electrons into the PCN conduction band through π–π* stacking interactions, creating an additional charge-transfer pathway. These results confirm that charge differences within the structure generated an internal electric field that effectively promoted electron-hole separation.
Figure 5. In situ diffuse-reflectance Fourier-transform infrared spectra, electrostatic-potential maps, and frontier-orbital distributions.
The S0→S25 transition of AN-CN exhibited a pronounced D-index value, clearly indicating charge-transfer excitation. This conclusion was supported by visualization of the hole-electron isosurfaces, where the centroids of the pink and blue isosurfaces were spatially separated.
By contrast, the centroids associated with other electronic transitions overlapped closely, confirming their locally excited character. The results indicate that strong electronic conjugation introduced by –NH₂ bonding further increased the electron density of the pyridine rings and promoted the separation of photogenerated charge carriers.
Figure 6. Charge-transfer mechanisms and charge-density distributions of N-CN, HN-CN, and AN-CN.
This study demonstrates that efficient photocatalytic H₂O₂ production can be achieved by introducing electron traps with active adsorption sites into the carbon nitride framework.
Using a one-step synthesis strategy, biocompatible nicotinic-acid derivatives were covalently immobilized onto tubular carbon nitride. This modification synergistically promoted exciton dissociation and strengthened O₂ adsorption, enabling efficient photocatalytic synthesis of H₂O₂ under mild conditions.
Importantly, the work systematically compared the synergistic effects of different functional groups and pyridine rings on the H₂O₂ production rate, providing mechanistic insights into molecular-level design principles for high-performance carbon nitride photocatalysts.
Guangfu Liao, Corresponding Author: Professor at Fujian Agriculture and Forestry University. He has been selected for the Young Elite Scientists Sponsorship Program of the China Association for Science and Technology, the Minjiang Scholar Distinguished Professorship, Fujian Province High-Level Category C Talent Program, and the university’s Hundred-Talent Climbing Program. He was named an Emerging Investigator by Journal of Materials Chemistry A in 2022 and by Chemical Communications in 2023.
Professor Liao serves on the early-career editorial boards of journals including eScience, Advanced Fiber Materials, and Exploration. His research focuses on the development and application of photocatalytic technologies and the high-value utilization of biomass, including photocatalyst design, catalytic conversion, mechanistic analysis, and theoretical calculations.
Over the past five years, he has published more than 60 high-level papers as first or corresponding author in journals including Nature Communications, Energy & Environmental Science, Matter, Angewandte Chemie, Advanced Functional Materials, and eScience. His work has received more than 7,100 citations, with an h-index of 50, and 11 papers have been selected as ESI Highly Cited Papers. He holds 11 authorized Chinese invention patents and has led multiple research projects, including National Natural Science Foundation of China programs.
Qing Li, Corresponding Author: Associate Professor and graduate supervisor at Hubei University. He has been recognized through a provincial-level talent program in Hubei and serves as an innovation and entrepreneurship mentor. He is also a young editorial-board member for journals including Engineered Science, Smart Molecules, Renewable and Sustainable Energy, and Eco-Environment & Health.
His research interests include the design and preparation of photocatalytic materials for energy and environmental applications, as well as the synthesis, physicochemical properties, and low-dielectric and ultraviolet-shielding applications of hyperbranched polyimides and polyimide-based nanocomposites.
He has led more than ten projects funded by the National Natural Science Foundation of China and provincial or ministerial research programs. As first or corresponding author, he has published more than 30 papers in journals including Progress in Materials Science, Trends in Biotechnology, Chemical Engineering Journal, Chinese Journal of Catalysis, and Materials Reports: Energy. He holds more than ten authorized Chinese invention patents.
Yuan Xue, Yanjun Zhang, Jun Du, Zushun Xu, Guangfu Liao, and Qing Li. “Introducing Dual-Functional Site on Carbon Nitride: Steering Carrier Migration and O₂ Activation for Boosted H₂O₂ Photosynthesis.” Acta Physico-Chimica Sinica, 2026, 100311.
https://doi.org/10.1016/j.actphy.2026.100311
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